The present invention relates generally to light pipes, also referred to as light guides and light plates, which carry light from a light source to a desired area.
More specifically, the present invention relates to light pipes for keyboards having illuminated key members.
Conventional keyboards include a plurality of key members which display symbols, such as alphanumeric keys, on their top surfaces. Moreover, typical modern keyboards, such as those found in cellular telephones, Automatic Teller Machines (ATMs), electric typewriters and computers utilize a make-and-break electrical circuit which is activated by depression of a key member for identifying a particular symbol embedded on the top of the key member.
A problem with prior art keyboards is that it is often difficult to discern the symbol appearing on the top of the key member under poor lighting conditions. This causes the keyboard operator to memorize the key locations or to strain their eyes to operate the keys of the keyboard under low light conditions. This has become a much greater problem in present day society as keyboards have become necessary for everyday use and as keyboard use is not limited primarily to operation by workers in business offices as in the past. As a result of this expansion of keyboard use, more and more operators have less training on keyboards, and correspondingly many keyboard operators utilize a “hunt and peck” style of keyboard operation.
Moreover, the advent of laptop and notebook computers has resulted in the use of keyboards at places where they were not previously operated. Often these places provide limited light making it difficult for keyboard operators to quickly and easily operate the keyboard. For example, it is a common sight on commercial aircraft to see a passenger slowly hunt and peck at their keyboards continuously looking at the key members to verify that they are in fact pressing the correct keys.
Accordingly, it is clear that there is a need for an apparatus that makes keyboard key members more discernable in low light conditions. Backlighting is commonly used in rubber keypads, membrane switches, rigid panels and the like to make them more visible and discernable. These keypad panels typically make use of light emitting crystals (LECs), light emitting diodes (LEDs), and/or fiberoptics for this purpose. Most prior backlit keyboards utilize a light source which is typically transmitted via a fiberoptic cable to the key members of a keypad. For example, U.S. Pat. No. 5,034,602 issued to Garcia, Jr. et al. discloses an optically activated keyboard which uses fiberoptic cables to transmit light to translucent key members. The light is transmitted through the translucent key members where it is emitted from the top of the key cap. Similarly, U.S. Pat. No. 3,886,544 issued to Narodny and U.S. Pat. No. 5,097,396 issued to Myers disclose keyboards which use backlighting. Each key member in connection to a fiberoptic cable which transmits light to a respective key member which thereafter transmits light from the top of the key cap. Additional keyboard and keypad techniques include the LED and LEC backlighting commonly utilized for alarm activator and deactivator keypads wherein each key includes a separate LED or LEC structure embedded in or behind the key member. Unfortunately, it is extremely difficult to route fiber optics to the keyboard keys of today's computer systems. For example, it would be particularly difficult to route fiberoptic cables and provide a light source to the key members of today's notebook computers and palm-sized computer systems.
In addition, the light sources for use with prior art backlit keyboards require substantial power and in some cases, a fan for cooling which draws additional power. These constructions are prohibitive for portable computers such as laptop and notebook computers which draw on the power of a rechargeable battery and where power is at a premium.
Recently, the present named inventor, Michael Shipman, developed numerous lighted keyboard constructions which are the subject of U.S. Pat. Nos. 6,217,183; 6,467,924 and 6,918,677 and which are incorporated by reference herein. The keyboard constructions utilize a variety of electro luminescent, light transmitting panels and light emitting diodes (LED) for illuminating the keys of a keyboard. For the most part, these constructions are satisfactory. However, electro luminescent light sources are very expensive and the alternative constructions require using several LEDs to adequately and uniformly illuminate a keyboard, which by their quantity, also makes the keyboard prohibitively expensive for mass market distribution.
Accordingly, there is a need for an improved light distribution construction, such as a light guide, which is less expensive than previous designs.
Accordingly, it would be highly advantageous to provide a light guide for a keyboard having illuminated key members suitable for use with today's computer systems including portable computers.
It would also be highly advantageous to provide a keyboard having illuminated keys which does not require routing of fiberoptic cables to each key member.
In addition, it would be highly advantageous to provide a keyboard having illuminated key members which is lightweight, simple and inexpensive to manufacture, and requires low power consumption.